848 HANDBOOK OF PHYSIOLOGY ^ NEUROPH^•SIOLOGY II 



LUMBAR 



CERVICAL 



FIG. 9. Maps from two monkeys (Dial anesthesia) showing cortical regions from which pyram- 

 idal responses were evoked in the lateral column at Li {left) and the lateral column at Ci (right) 

 obtained with diflTerent stimulus intensities. Responses from stimulating stippled regions showed 

 Vjoth D and I waves, those from areas with horizontal bars only I waves. Stimulus (o. i msec.) moni- 

 tored and kept constant throughout; upper map, 41.5 ma; loiver map, 59 ma. D waves from the post- 

 central gyrus probably resulted from current spread. 



FIG. 10. Cortical regions from which antidromic potentials are recorded following stimulation 

 of bulbar pyramid in cat (left) and monkey' {right). Heavily hatched areas, large responses; lightly 

 hatched areas, small responses. [From Woolsey & Chang (112).] 



tosensory area 1 is shown in figure 1 3 in which a Betz 

 cell was fired by either contralateral or ipsilateral 

 forepaw stimulation. Whether recorded as unitary 

 responses (fig. 13) or as multiunit pyramidal dis- 

 charges (figs. II, 19), the ipsilateral response is 



characteristicallv more Iragilc and variable and has a 

 longer latency than the contralaterally evoked dis- 

 charge. In single-unit recording, lower firing proba- 

 bility and greater variation in the number ol spikes in 

 the train and in the latency of the first spike distin- 



